What is the cosine function?

Cosine gives the ratio of the adjacent side to the hypotenuse in a right triangle, or the x-coordinate on the unit circle.

How are sine and cosine related?

sin²(x) + cos²(x) = 1 (Pythagorean identity). Also, cos(x) = sin(90° - x) and vice versa.

Cosine equals zero at 90° and 270° (and every 180° offset from those).

Cosine Calculator

Calculate the cosine of an angle in degrees. Also shows sine and tangent.

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Angle (degrees)

deg

Cosine Val

0.50000000

Sine Val0.86602540

Tangent Val1.73205081

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Cosine Function

Definition

In a right triangle, cos(angle) = adjacent / hypotenuse.

On the unit circle, cos(angle) is the x-coordinate of the point at that angle.

Key Values

Anglecos 0°1 30°√3/2 ≈ 0.8660 45°√2/2 ≈ 0.7071 60°0.5 90°0

Example Calculation

Calculate cos(60°).

01cos(60°) = 0.5
02sin(60°) = √3/2 ≈ 0.8660
03tan(60°) = √3 ≈ 1.7321

Frequently Asked Questions

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Related Calculators

Sine Calculator

Calculate sine values.

Tangent Calculator

Calculate tangent values.

Inverse Cosine Calculator

Calculate arccos values.